Method and apparatus for removal of cooling water from ingots by means of water jets

ABSTRACT

The exemplary embodiments relate to the removal of cooling water used to cool the surface of an ingot as it is formed during casting. The cooling water is removed from the surface by directing jets of water onto the surface at an angle, and with a momentum, that causes the cooling water to be stripped from the surface when contacted with the jets, and to follow a path that prevents the cooling water from again coming into contact with the ingot surface at a position beyond the point of removal. The apparatus for this includes nozzles to create the water jets, and equipment for supplying water under sufficient pressure and rate of flow to the nozzles.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority right of prior provisionalapplication Ser. No. 61/131,283 filed Jun. 6, 2008 by applicants herein.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to casting of metal ingots. More particularly,the invention relates to the cooling of such ingots as they emerge froma casting apparatus by the application and removal of cooling water tothe outer surfaces of the ingots.

(2) Description of the Related Art

There are various techniques for casting metal ingots, such as directchill (DC) casting (a technique that includes electromagnetic casting(EMC)), hot top technologies for the production of rolling slab ingots,forging ingots, extrusion ingots (billets), etc. These various castingtechniques may involve the application of cooling media to the externalsurface of the ingots as they emerge from the mold to ensure ingotsurface solidification and to reduce the likelihood of molten metalbleedout from the interior of the ingot before the ingot becomes fullysolid. Frequently, the ingots are cast vertically, but horizontalcasting is also practiced as, for example, in horizontal direct chillcasting (HDC). In the case of vertical direct chill casting, inparticular, cooling water is directed onto the outer surface of theingot around the bottom of the mold and the cooling water flows down thesides of the ingot.

For some purposes, it is desirable to remove the cooling water from thesurface of the ingot at a certain distance from the mold exit. Thisreduces the rate of cooling of the ingot from that point on because thesurface becomes air cooled rather than water cooled. As shown, forexample, in U.S. Pat. No. 4,237,961 to Zinniger on Dec. 9, 1980, thecooling water may be removed by means of physical wipers orsqueegee-like devices that contact the metal surface, but the surface ofthe ingot is still hot and wiper devices may quickly become degraded,especially if there is an instance of molten metal bleed-out that bringsmolten metal into contact with the elastomeric material of the wiper orthe metal of the supporting structure. It may also be difficult toemploy mechanical wipers of this kind at an early stage in the castingprocess. The geometry of the butt (bottom) of the ingot makes mechanicalwiping schemes difficult, especially in the case of thin ingots. Forexample, in DC casting, during the initial fill, start down, primary andsecondary curl, metal sometimes dribbles or bleeds out of the mold andthe molten metal may collect on the wiper and burn the elastomericcontact material prior to its being able to wipe the ingot. Therefore,the wiper is not usually deployed until after the incidence ofbutt-curl, i.e. only after the ingot has emerged by 10 to 14 inches.Wipers which mechanically engage the ingot cannot be engaged prior tofinal curl, so again the first 10 to 14 inches of the ingot issubstantially cooled prior to any water being removed. After wiperengagement, the dissimilar temperatures between the butt portion and runportion generates varied metallurgical structures and stresses which canresult in further processing problems or the formation of scrap whilecasting, preheating and rolling.

It is known to remove cooling water by means of jets of gas, such ascompressed air, that blow the cooling water from the cast metal, forexample as disclosed in U.S. Pat. No. 2,705,353 to Zeigler which issuedon Apr. 5, 1955. However, compressed air wipers are costly to installand use because of inefficiencies involved in pressurizing compressiblegases.

U.S. Pat. No. 5,685,359 to Wagstaff et al. shows coolant spray holeswith overlapping spray patterns for use in direct secondary cooling, butthe spray holes are not used for coolant water removal.

U.S. Pat. No. 5,431,214 to Ohatake et al. mentions cooling water jets,but again such jets are not used for coolant water removal.

There is a need for improved ways of removing surface cooling water fromsuch ingots.

SUMMARY OF THE INVENTION

An exemplary embodiment of the invention provides a method of removingcooling water from a surface of a metal ingot, wherein the cooling waterstreams over the surface in a casting direction. The method involvesdirecting one or more water sprays onto the surface of the ingot at anangle and rate of flow effective to cause the cooling water streamingover the surface to separate from the surface as the cooling waterencounters the sprays. Preferably, enough of the cooling water isremoved to allow natural film boiling to occur, thereby removing all ofthe cooling water within a short distance of the water sprays.

Another exemplary embodiment provides an apparatus for removing coolingwater from a surface of a metal ingot, wherein the cooling water streamsover the surface in a casting direction. The apparatus includes one ormore nozzles adapted to direct water sprays onto the surface, thenozzles being positioned and angled such that the water sprays areeffective in use to cause the cooling water streaming over the surfaceto separate from the surface as the cooling water encounters the sprays.The apparatus also includes one or more conduits for supplying water tothe nozzles, and pressurizing apparatus for pressurizing water suppliedto the nozzles.

According to these exemplary embodiments, water jets or sprays are usedto remove cooling water from the surface of an ingot as it is beingcast. The apparatus for producing the water jets is economical toprovide and operate given that the removal medium is water (which may betaken from the same source as the water used for cooling the ingot). Theapparatus and method may be used early during casting operations andclose to the outlet of the casting mold as the jets are not affected bymolten metal bleed out and they follow any variations in the profile ofthe ingot as it is being produced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-section of a known direct chill casting moldprovided with a mechanical wiper for removal of cooling water;

FIG. 2 is a horizontal cross-section of an ingot being cast by DCcasting showing an exemplary embodiment of apparatus for removingcooling water;

FIG. 3 is an enlargement of part of the apparatus of FIG. 2, showingwater jets in action;

FIG. 4 is a vertical section of part of the apparatus of FIG. 2 prior toactivation of the water jets;

FIG. 5 is the same view as FIG. 4 but showing the apparatus followingactivation of the water jets;

FIG. 6 is a vertical cross-section similar to that of FIG. 5 but showingan exemplary embodiment that makes use of a scupper to remove coolingwater;

FIG. 7 is a horizontal cross-section of an alternative exemplaryembodiment that makes use of a corrugated shield wall to form channelsfor cooling water stripped from the ingot surface.

FIGS. 8 to 10 illustrate alternative embodiments making use of narrowcylindrical water jets to remove cooling water from an ingot; and

FIG. 11 is a cross-section illustrating an exemplary embodiment appliedto horizontal DC casting.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The exemplary embodiments of the present invention may be used withapparatus of many kinds that employ streams of water to cool anewly-formed metal ingot, e.g. an ingot of a non-ferrous or light metal,such as an ingot of an aluminum, magnesium or copper alloy. However, theexemplary embodiments are especially suitable for use with DC castingapparatus and one form of such apparatus is shown in FIG. 1 and isbriefly described below so that the preferred and exemplary embodimentsmay be better understood, although it is to be noted that the presentinvention is not limited to equipment of this kind.

FIG. 1 is a vertical cross-section of a direct chill casting moldproducing a metal ingot and showing a known arrangement for removingcooling water from the outer surface of the ingot. This apparatus isdisclosed in U.S. patent publication no. 2007/0102136 to Wagstaff etal., published on May 10, 2007 (the disclosure of which is specificallyincorporated herein by this reference). The mold is indicated generallyat 10 and it is provided with an open upper entrance 11 and an openlower exit 12. Molten metal is introduced into the entrance of the moldas indicated by arrow 13. The mold includes a primary cooling channel 14filled with recirculating cooling water 15 that cools the inner wall ofthe mold. The molten metal cools adjacent to the mold wall and forms anembryonic ingot 16 that emerges from the mold. The embryonic ingot has amolten metal sump 17 surrounded by a solid metal shell 18 whichincreases in thickness as the ingot descends until full solidificationoccurs at a point remote from the exit 12 of the mold to form a fullysolid ingot 19. Streams or jets of cooling water 20 are poured onto thesurface of the ingot from the channel 14 adjacent to the lower exit 12of the mold to help to form 5 and maintain the solid outer shell 18around the molten metal sump. The water streams down along the sides ofthe embryonic ingot, but is removed by a mechanical wiper 21 positionedat a distance X from the exit of the mold. The cooling water 20 removedin this way forms streams 22 spaced from the ingot 19 that have nofurther cooling effect. The wiper is in the form of an annulus made of asoft flexible or elastomeric material that physically contacts the outersurface of the ingot to wipe away the cooling water. The wiper is heldin a rigid holder (not shown) made of metal or the like. In theapparatus of FIG. 1, distance X is made such as to allow the ingot to“self homogenize”. Of course, there are other reasons why the coolingwater may be removed at a predetermined distance from the mold, so theexemplary embodiments are not limited to this one purpose.

In preferred exemplary embodiments of the present invention, amechanical wiper of the kind shown at 21 may be replaced by a series ofwater jets that remove the cooling water from the surface of the ingot.This is shown by way of example in FIGS. 2 to 11 of the accompanyingdrawings. FIG. 2 shows a horizontal cross-section of an ingot at adistance below a direct chill casting mold where cooling water is to beremoved. The ingot 19 (or embryonic ingot 16) having a downwardlystreaming surface layer of cooling water 20 is completely surrounded ata narrow horizontal spacing by a short solid vertical wall 25 (made, forexample, of a metal such as aluminum or stainless steel) that extendsdownwardly from a bottom wall 26 of a direct chill casting mold 10 (seeFIGS. 4 and 5). The wall 25 is not essential, but acts as a shield toprevent water from spraying onto any other ingots that may be cast atthe same time in adjacent areas. The wall 25 is penetrated by a numberof holes or slots 27 all positioned at the same vertical height in theillustrated embodiment. An elongated nozzle 28 extends through each slotfrom outside the wall and terminates a short distance from the outersurface 29 of the ingot. As best seen in FIG. 2, the nozzles 28 on eachside of the ingot 19 are connected to a manifold 30 that supplies waterunder pressure to the nozzles, and the manifolds are connected togetherin series by high pressure flexible hoses 31, 32 and 33. The firstmanifold in the series is connected by a flexible high pressure hose 34to an apparatus 35, e.g. a pump, for supplying water under pressure.When supplied with water under pressure in this way, the nozzles eachspray a jet 36 (FIG. 3) of water towards the surface 29 of the ingot. Itwill be noted that each of the nozzles forms a jet 36 having the shapeof a flat fan of water. Thus, the jets 36 are generally flat in verticalside view but expand outwardly in plan view, so that they extendvertically by a much smaller distance than they extend horizontally. Thefan shaped jets 36 are preferably partially overlapping, as shown. Theangle at the apex of the water jets (as shown in the plan view of FIG.3) is preferably at least 65°, and may be 72°, or more. The nozzles arepreferably spaced from each other (and/or from the ingot) by distanceseffective to provide an overlap of the water jets of 1-2 inches at theingot surface 29. While this arrangement is particularly preferred, itwill be noted from later embodiments that nozzles producing water jetsof other shapes may alternatively be employed, e.g. cylindrical jets,and that overlap of the jets may not always be necessary.

The manifolds 30 may be of any size and shape, but are preferably squarein cross-section (e.g. of 1¼ inches per side) and the nozzles 28 arepreferably arranged at intervals of up to about 5 inches from eachother, although this may be varied to suit particular molds and spacingarrangements. For standard DC casting equipment, the manifolds 30 maybe, for example, 1720 mm long (long side of ingot) and 560 mm long(short side of ingot). The pressure of the water supplied to the nozzles28 should be adequate for the removal of most or all of the coolantwater from the surface of the ingot and is preferably at least 80 psi upto about 150 psi, and more preferably is in the range of 100-120 psi, togive a rate of flow at each nozzle of at least 0.4 gallons per minuteper linear inch of distance around the mold circumference (gpm/in) up toabout 1.5 gpm/in, (ideally in the range of 0.6-1.0 gpm/in). The molddischarge flow rate (flow rate relating to the overall water dischargefrom the mold in advance of the wipers) is preferably at least 0.6gpm/in up to about 1.5 gpm/in, and is preferably in the range of 0.7-1.0gpm/in. The high pressure hoses 31, 32, 33 and 34 are preferablyattached to the manifolds by quick release fittings so that they may beeasily disconnected and re-connected to allow the replacement of one ormore of the manifolds if they become blocked or otherwise requireattention. Moreover, the manifolds 30 are preferably supported onequipment (not shown) that allows them to be moved closer to or furtheraway from the ingot 19, and/or closer to or further away from thecasting mold. Also, it is desirable to make the nozzles rotatable abouta horizontal axis to make it possible to adjust the angle of sprayrelative to the ingot surface, as circumstances dictate.

The action of the jets is best shown in FIGS. 4 and 5, which aredetailed vertical sectional views in the region of the bottom wall 26 ofthe casting mold 10. The manifolds 30 have been omitted from thesedrawings for the sake of simplicity but are positioned immediatelyoutside the walls 25. FIG. 4 shows the situation before the jets arestarted. Nozzles 28 extend through the vertical wall 25 and face thesurface 29 of the ingot 19 emerging from an exit 12 of the casting mold.Cooling water 20 is streamed onto the surface 29 from apertures in thebottom of channel 14 of the mold and the water streams in a continuouslayer downwardly along the outer surface of the ingot (as represented byarrow A). Without operating the water jets, the cooling water streamsdown the ingot in this way until it reaches the bottom of the ingot or awater collection pool. As shown in FIG. 5, in order to remove thecooling water at distance X from the bottom of the mold, the nozzles 28are supplied with water under pressure to create flat fan-shaped jets 36of water that contact the surface 29 of the ingot. When the jets havesufficient momentum (volume of water and rate of flow), and a suitableangle α relative to the surface 29 (preferably in the range of 65 to75°, and more preferably 68 to 72°) with a component of movementcountercurrent to the direction of flow of the cooling water 20, theystrip the cooling water 20 from the ingot surface and force it to adoptan upward flow 40 (as indicated by arrow B) after leaving the ingotsurface 29. This means that the nozzles 28 are preferably angledupwardly from the horizontal (when the streams 20 flow downwardly) at anangle of 15 to 25°, and more preferably 19 to 22°, although the mosteffective angle may be determined in particular situations by trial andexperimentation. The overlap of the jets further helps to remove thestreaming water from the ingot because the momentum created by the waterin the overlap region helps to cause the streaming water to spray awayfrom the ingot with an “interactive fountain” effect. Ideally,sufficient cooling water is removed in this way to leave just a thinresidual film that quickly dries off due to the high temperature of theingot.

Preferably, the upward flow 40 of cooling water is caused to bounce offthe bottom wall 26 of the casting mold without impacting the junctionbetween the ingot and the mold and entering the mold cavity, and is thencaused to run down the inside surface 42 of the vertical wall 25 (asindicated by arrow C) so that there is no further contact between thecooling water and the surface 29 of the ingot beyond distance X. Thecooling water is thus stripped from the surface without any directcontact from mechanical parts of the apparatus.

It should be noted that sufficient cooling water should be stripped fromthe surface 29 to achieve a desired reduction of cooling of the ingotbeyond distance X. Ideally, all or substantially all of the coolingwater is removed in this way, but this is not always essential (orperhaps possible) because small amounts of cooling water remain beyonddistance X. However, these residual amounts normally disappear quicklyor even instantly due to evaporation caused by the heat of the ingot.Also, according to the cooling effect desired in any particular case, asmall amount of residual cooling water may be acceptable, even if itdoes not disperse immediately by evaporation. Preferably, at least 90%of the volume of the cooling water above point X, more preferably atleast 95%, and even more preferably at least 99%, is removed by thewater jets themselves to leave just a sub-film that is quickly or evensubstantially instantly removed by evaporation.

The spacing of the nozzles from the ingot is preferably optimizedaccording to the following considerations. The closer the nozzles arepositioned to the ingot, the higher will be the momentum of the water inthe jets as they contact the ingot surface, but the more at risk thenozzles will be from damage if molten metal bleeds out of the mold oringot during the casting operation. Also, the closer the nozzles arepositioned to the ingot, the greater the number of nozzles will berequired in order to provide a constant line of impacting water aroundthe entire periphery of the ingot. Therefore, the spacing of the nozzlesfrom the ingot should be made as far as possible without causing themomentum of the water in the jets to diminish to a point below theireffectiveness for stripping cooling water from the ingot.

The distance X at which the water jets are applied to the ingot surfacedepends on the reason for the desired water stripping operation. Asnoted above, the water stripping may be required for “in-situhomogenization”, in which case the distance X is one that allows thetemperature of the ingot to rise to the homogenization range followingwater stripping. Cooling water removal may alternatively be carried outfor stress relief within the ingot. In the case of more conventionalwiping used with hard alloys, a greater distance X is employed and aflash boiling effect of any residual cooling water may not be soimportant.

It should also be noted that the distance X may, in some cases, bechosen to differ on different sides of the ingot. The short sides of theingot (ingot ends) may have a jet contact point that is higher (closerto the mold) than that required for the long faces of the ingot (rollingfaces). Also, thinner ingots may have water contact points that arehigher than those required for thicker ingots. However, the rate of flowand pressure of the water jets would normally be the same on all sidesof the ingot, unless the streaming water is acted upon by a differentforce on different sides of the ingot (e.g. gravity in the case ofhorizontal direct chill casting). In such a case, the flow rate and/orpressure would be varied on different sides of the ingot to achieve thedesired degree of water stripping from each ingot face.

The ideal angle of the nozzles to produce the cooling water strippingeffect can be determined by manually adjusting the angle of the jets(e.g. by rotating the manifolds 30) and observing the results. This maybe done in a preliminary run of the casting apparatus and thenmaintained at the same angle for all subsequent casting runs of the samecharacteristics.

It should be noted that the exemplary embodiments of the presentinvention may be especially effective when used with the means ofcooling water application disclosed in U.S. Pat. No. 5,685,359 toWagstaff mentioned above. This means of cooling employs a split jet/dualjet arrangement for ingot cooling purposes at the exit of the castingmold.

For reasons of safety, performance and maintenance, the hoses andmanifolds through which the water passes will need filters, shut offvalves and other conventional equipment. For example, a 50 mesh filtermay be provided to protect the nozzles from blockage. Such a filter maybe provided on the supply side of the apparatus 35 for supplying thewater under pressure in order to minimize loss of performance of theapparatus. The apparatus 35 may be a pump capable of generating forexample 150 psi or more of water pressure and a rate of water flow of115 gallons per minute or more. Suitable pumps may be obtained, forexample, from Pioneer Pump Inc., of 310 South Sequoia Parkway, Canby,Oreg. 97013, U.S.A. (e.g. model SC32C10). The same water that is usedfor cooling may be employed for the nozzles, or it may be supplied froma different source. The water may be substantially pure, but may containvarious additives, such as ethylene glycol. When the water contains suchadditives, it must of course be supplied from a source different fromthe cooling water. The water may also contain unintentional additives,particularly if recycled cooling stream water is used. The water isgenerally at ambient temperature when fed to the nozzles.

The nozzles 28 are preferably capable of delivering about 0.8 to 1.0 (oreven 1.5 or more) gallons of water per minute over an arc of at least65° (preferably 72°) at a pressure of 120 psi. Such nozzles may beobtained, for example, from Spraying Systems Co. of P.O. Box 7900,Wheaton, Ill. 60189-7900, U.S.A. The nozzles are preferably used withextenders to allow them to project sufficiently through the shield wall25 to avoid interruption by contact with the reverse flow of coolingwater streaming along the inner surface of the wall.

An alternative embodiment is shown in FIG. 6. In this embodiment, theunderside 26 of the mold 10 is provided with a scupper 50 to collect thecooling water 20 stripped from the ingot 19 before it descends down wall25 to the level of the nozzles 28. This avoids the possibility that thestripped cooling water may interrupt or adversely affect the operationof the nozzles 28 or the shape or power of the water jets 36. Watercollected in the scupper 50 flows to the ends of the mold and is allowedto pour away from the ingot or is removed through suitable channels (notshown).

Another alternative arrangement is shown in FIG. 7 which makes use of ashield wall 25 having a corrugated shape in plan view. The nozzles 28project through the wall 25 at positions where the wall is closest tothe surface 29 of the ingot 19. After curling back away from the ingotin the manner shown in FIG. 5, cooling water 20 stripped from the moldby the jets 36 tends to stream into the vertical channels 52 formedbetween the points of the wall 25 closest to the ingot. This directs thecooling water away from the nozzles 28 and water jets 36, therebyminimizing any likelihood of interference with the jets.

FIGS. 8 to 10 show embodiments where narrow cylindrical water jets areused instead of the fan shaped jets of the above embodiments. In FIG. 8,the jets 36 (which are upwardly angled as in previous embodiments)penetrate the layer of cooling water 20 to the surface 29 of the ingot19 and then spread out to separate the cooling water from the ingotsurface. In the case of FIG. 9, after contacting the ingot 19, the jets36 spread sufficiently to contact each other and form a combined“interactive fountain” 54 between the positions of the nozzles. Thiseffect is created by adjusting the pressure and flow rates of thenozzles sufficiently. The cooling water layer becomes completelyseparated from the ingot.

In the case of FIG. 10, the effect shown in FIG. 9 is accentuated byangling the nozzles towards each other to maximize the separation of thecooling water from the ingot surface.

FIG. 11 shows an exemplary embodiment of the invention applied tohorizontal DC casting. In horizontal direct chill casting apparatus, thepositions of the nozzles may have to be adjusted to allow the waterwiping jets to contact the top surface of the ingot at a differentdistance from the casting mold relative to the bottom surface of theingot. In addition, in the illustrated embodiment, a scupper 50 is usedat the upper side of the ingot to collect and remove cooling water 20stripped from the ingot. Without such a means of collecting and removingthe stripped cooling water, it would fall back on the ingot andadversely affect the cooling characteristics of the ingot. At the lowerside of the ingot, cooling water 20 may fall naturally from the ingot 19as shown, or alternatively a series of water jets may also be applied toremove the cooling water at a distinct distance from the mold. However,a scupper such as the one 50 used at the upper side of the mold, willnot be needed at the lower side of the mold because cooling waterstripped from the ingot will anyway stream away from the ingot under theaction of gravity. As in the embodiment of FIG. 6, the scupper 50removes the collected cooling water to the ends of the mold and disposesof it without allowing it to come into contact with the ingot or thenozzles.

While the embodiments described above are preferred, variousmodifications and alternatives are possible. As already noted, theexemplary embodiments may be employed with various kinds of castingapparatus, not just the DC casting apparatus of FIG. 1. Moreover, theinvention is suitable for use with metals of various kinds, particularlyalloys of aluminum, magnesium and copper. Use with the casting ofaluminum alloys is particularly preferred.

1. A method of removing cooling water from a surface of a metal ingot,wherein said cooling water streams over said surface in a castingdirection, the method comprising: directing one or more water spraysonto said surface at an angle and rate of flow effective to cause saidcooling water streaming over said surface to separate from said surfaceas said cooling water encounters said one or more water sprays.
 2. Themethod of claim 1, wherein said water sprays are directed onto saidsurface at an angle within a range of 65 to 75 degrees in a directioncountercurrent to said streaming direction.
 3. The method of claim 1,wherein said water sprays each have a rate of flow of up to about 1gallon per minute.
 4. The method of claim 1, wherein said water spraysmade generally flat and fan shaped.
 5. The method of claim 4, whereinsaid fan shaped sprays are positioned close to one another so that thesprays overlap where the sprays contact the ingot.
 6. The method ofclaim 4, wherein said water sprays are positioned close to each other sothat the amount by which said sprays overlap is in the range of 1 to 2inches.
 7. The method of claim 4, wherein said sprays each extend overan arc of at least 65 degrees.
 8. The method of claim 1, wherein saidnozzles are separated from each other by a distance of up to 5 inches.9. The method of claim 1, wherein said cooling water removed from saidsurface by said sprays, and water from said sprays after contact withsaid surface, is constrained to follow a path remote from said surfaceof the ingot.
 10. The method of claim 1, wherein said cooling waterremoved from said surface, and water from said sprays after contact withsaid surface, is maintained out of contact with said surface butconfined to a region surrounding said ingot.
 11. The method of claim 1applied to an ingot emerging from a direct chill casting mold providedwith orifices applying said cooling water to said surface of said ingot,wherein said sprays are all directed onto said surface at apredetermined distance from said direct chill casting mold.
 12. Themethod of claim 11, wherein said ingot is generally rectangular and hasfour sides, and wherein said sprays are directed onto all said foursides of said ingot at said predetermined distance from said directchill casting mold.
 13. The method of claim 11, wherein said directchill casting mold is orientated for vertical casting.
 14. Apparatus forremoving cooling water from a surface of a metal ingot, wherein saidcooling water streams over said surface in a casting direction, saidapparatus comprising: one or more nozzles adapted to direct water spraysonto said surface, said nozzles being positioned and angled such thatsaid water sprays are effective in use to cause said cooling waterstreaming over said surface to separate from said surface as saidcooling water encounters said sprays; one or more conduits for supplyingwater to said nozzles; and pressurizing apparatus for pressurizing watersupplied to said nozzles.
 15. The apparatus of claim 14, wherein saidone or more nozzles are orientated at an angle to said surface within arange of 65 to 75 degrees in a direction countercurrent to saidstreaming direction.
 16. The apparatus of claim 14, wherein said watersprays are rated for a flow of up to about 1.5 gallons per minute. 17.The apparatus of claim 14, wherein said nozzles are configured togenerate water sprays that are generally flat and fan shaped.
 18. Theapparatus of claim 14, wherein said nozzles are positioned close to oneanother so that the sprays overlap where the sprays contact the ingot.19. The apparatus of claim 18, wherein said nozzles are positioned closeto each other so that the amount by which said sprays overlap is in therange of 1 to 2 inches.
 20. The apparatus of claim 17, wherein thenozzles are configured such that the fan shaped sprays each extend overan arc of at least 65 degrees.
 21. The apparatus of claim 14, whereinsaid nozzles are separated from each other by a distance of up to 5inches.
 22. The apparatus of claim 14, wherein said nozzles areconfigured such that said cooling water removed from said surface bysaid sprays, and water from said sprays after contact with said surface,is constrained to follow a path remote from said surface of the ingot.23. The apparatus of claim 14, wherein said nozzles are configured suchthat said cooling water removed from said surface, and water from saidsprays after contact with said surface, is maintained out of contactwith said surface but confined to a region surrounding said ingot. 24.The apparatus of claim 14 including a direct chill casting mold forproducing said ingot, said mold being provided with orifices applyingsaid cooling water to said surface of said ingot, wherein said nozzlesare positioned at a predetermined distance from an outlet of said directchill casting mold.
 25. The apparatus of claim 24, wherein said ingot isgenerally rectangular and has four sides, and wherein said nozzles arepositioned on all said four sides of said ingot at said predetermineddistance from said direct chill casting mold.
 26. The apparatus of claim24, wherein said direct chill casting mold is orientated for verticalcasting.